1. Field of the Invention
The present invention relates to a smoking device for heat-decomposing main-flow smoke and sub-flow smoke of a cigarette, thereby detoxicating the main-flow smoke and sub-flow smoke.
2. Description of the Related Art
Cigarette smoke consists of main-flow smoke (main stream), which is white smoke inhaled by a smoker from a cigarette tip, and sub-flow smoke (side stream) arising from a burning end of the cigarette.
In general, cigarette smoke contains about 4000 or more chemical substances, and about 200 or more of them are harmful to health. Of these, nicotine, carbon monoxide, tar, benzpyrene and nitrosoamine are particularly harmful.
The sub-flow smoke contains a greater amount of harmful substances than the main-flow smoke. If a non-smoker is exposed to the sub-flow smoke, the non-smoker's health is damaged. Under the circumstances, a movement isolating the non-smoker's space and time from the smokers' has been developed. As measures for such movement, there has been proposed some devices or methods. For example, an ashtray is provided with a filter having a fan, an ashtray is provided with a purifying unit such as a minus-ion generator, or air with smoke is purified by an activated carbon-containing filter which covers the entire cigarette.
Cigarette smoke consists of a particle portion and a gas portion. The particle portion can be substantially filtered by a purifying unit such as a filter, but it is difficult to remove the harmful gas portion from the cigarette smoke. In particular, the sub-flow smoke contains a considerable amount of harmful gas components, and it is difficult to instantaneously remove the harmful gas components through the purifying unit.
Compared to the above methods, a method of heat-decomposing the component of the cigarette is excellent in that not only particle component but also gas component is decomposed. The applicant of the present application has proposed various types of smoking devices using the heat-composition method. For example, the applicant's Published Unexamined Japanese Utility Model Application No. 2-90992 discloses a smoking device having a housing with an exhaust port and an air port. The housing defines a heating chamber in which a burning end of a cigarette is located. Main-flow smoke is introduced into the heating chamber. Within the heating chamber, the components of the main-flow smoke and sub-flow smoke of cigarette are heat-decomposed by an electric heater, a combustion device which produces a flame, or the like.
However, in the smoking device according to Application No. 2-90992, a large quantity of energy is required to heat-decompose the component of the main-flow smoke. When the main-flow smoke is introduced into the heating chamber, the flame of the combustion device having high portability and practicability may be extinguished by the air containing the main-flow smoke. These pose a serious problem in putting the smoking device into practical use.